Effect of Biotic Stress Due to Phyllophaga spp. on Antioxidant Compounds during Jicama Root (Pachyrhizus erosus) Development

Abstract

The levels of different nutraceutical metabolites present in the jicama root were measured when subjecting the plant to induced biotic stress via infestation with Phyllophaga spp. (white grubs). The change in secondary metabolites on the stressed jicama roots (SJ), mostly antioxidants, was followed over 100, 140, and 180 days and compared against the non-infested control jicama (CJ). Our results show that infested (SJ) samples contained higher concentrations of tannins, flavonoids, and total phenols, measured using spectrophotometric methods, peaking at 140 days, and higher overall concentration of saponins. SJ samples showed higher DPPH inhibition, peaking at 100 days. Chlorogenic acid had the highest concentration among the phenolic compounds (7.47 mg g−1), followed by protocatechuic acid, both in SJ, which was possibly related to the lower observed concentrations of caffeic and ferulic acids. As for flavonoids, we observed a high concentration of rutin in CJ and a low concentration of pelargonidin and myricetin in SJ, possibly promoted via the dihydrokaempferol pathway. Taken together, these results show that Phyllophaga spp.-mediated biotic stress affects the concentrations of secondary metabolites in the different maturity stages in jicama, having an effect on its metabolic pathways, which presents an opportunity for the use of material such as agro-industrial waste.